Sickle bar assemblies are used on agricultural equipment to cut crops. The assemblies in general include reciprocating cutting blades, also known as sickle sections that are attached to a metal bar commonly referred to as a knife back and move in a reciprocating motion over knife guards of the sickle bar assembly to cut crops. Examples of such sickle bar assembly systems may be seen in U.S. Pat. No. 8,371,096.
Thus, the reciprocating cutting blades function as one half of the cutting system, the other half being the sickle guards which the sickle sections cut against to form a scissor type of cutting action. The sickle/guard process of cutting crop has been around for over 150 years in various forms. Over the years attempts have been made to improve these particular components that make up the cutting systems through use of various materials and heat treatments in attempts to improve wear, efficiency, and cost of production.
In the efforts to improve cutting blade cutting efficiency, there has been some work on the design of the serrations on the sickle section in the past 40 years so as to help direct the crop stems to the root of the serration tooth. This has been shown to cause a self-sharpening effect as the blade is moving from left to right in use. At this point in time, this is the state of the art for all major agricultural equipment manufacturers. However, the wear life of this cutting system is not adequate. More specifically, the cutting edges of these sickle sections dull fairly quickly which in turn causes the load on the sickle to increase dramatically and thereby lead to more fuel usage and breakage of the sickle.
One attempt to help increase the cutting edge retention of the modern sickle section was developed around midcentury and it included the use of hard chrome plating on the entire sickle section. This hard chrome plating was fairly well accepted but alas the cost to plate the entire sickle section became prohibitive, and more recently, the environmental impact of chrome plating has made this approach obsolete.
In the middle 1980's a Kansas manufacturer introduced a “Tungsten Steel Sickle Section” touting a tungsten carbide hard-facing applied to the top of the serrations. The present inventor contemplates that a problem with this design is that the serrations could not fully accept the hard-facing and thus the wear resistance was still a problem. This product was only on the market a few years because the cost of the hard-facing was not worth the increased product life that was claimed.
Most recently, U.S. Pat. No. 6,857,255 disclosed a sickle section with laser hardened cutting edges. In the '255 patent, the cutting edges are quench and tempered to 40-58 Rc to remain fairly tough and then a secondary laser heat treating operation is applied to the very tips of the serrations of the cutting edge in the range of 64-68 Rc hardness. Unfortunately, this design results in the cutting edge having such a high hardness that it is extremely brittle and the teeth of the serrations may break off within minutes of operation leaving a dull cutting edge.
Lastly, as sickle sections are designed today, the present inventor contemplates that the forward facing tip of the reciprocating cutting blade can be a deterrent in allowing crop to enter the cutting zone comprising the cutting edges of the cutting system, because as the tips encounter the stalk of crop, the blunt impact merely knocks the crop down and does not allow for the crop to efficiently move as desired into the cutting edges. For this reason, the inventor further contemplates that the sickle sections are typically designed with a small width tip, however, such small tips are problematic because the smaller the tip gets the less strength it has to endure crop cutting and other obstacles in the field; the smaller the tip, the less effect it has on allowing crop into the cutting zone but, the more likely it is to break.
Different aspects of the invention seeks to address one or more of the foregoing limitations found by the present inventor in reciprocating cutting blades of sickle bar assemblies. These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.